My wife's Toshiba NB505 notebook has a display problem
in that after a few minutes from Startup the display
freezes with a sort of overlaying pattern.

The computer then will not respond to any of the
keyboard or mouse inputs, so it impossible to do
the Normal Shutdown. A forced shutdown by holding
the Power On/Off switch for several seconds works.

On the next Startup attempt it is possible to get into Safe
Mode, the display works all the time in this mode, normal
Shutdown is achievable in Safe Mode, but on the next
normal Startup the display problems happens.

The OS is Windows 7 basic version.

Where would one start to look for the solution,
I have ordered extra RAM and will see if that helps.